Surface-oriented wavefront synthesis

Taner (1976) proposed to synthesize plane wave sources at the surface by stacking traces in a common receiver gather. The stacked section can be migrated with the same concept as profile imaging. Now the downgoing wave is a plane wave at the surface and the upcoming wave is the stacked traces. The image by this approach represents the reflection coefficient at the normal incidence angle for a horizontal reflector and a non-zero incidence angle for a dipping reflector if the velocity is constant.

Schultz and Claerbout (1978) note that reflectors of different dips can be shown more clearly and used to estimate the velocity by synthesizing various slanted plane waves. By using various slanted plane wave stacks, we can illuminate the dipping reflector with the maximum amplitude of the reflection coefficient.

This analysis, however, is valid only within the shallow depth levels because the incident plane or slanted wavefront will be distorted at deeper levels due to variations of the velocity. Thus we can have more interpretable images of reflectors only within the shallow regions.